What is Biodiversity Net Gain (BNG)?

Biodiversity Net Gain (BNG) is an environmental policy approach designed to ensure that development projects leave the natural environment in a measurably better state for biodiversity than before the development took place.

In simpler terms, it means that when land is developed for housing or infrastructure, the developer must replace and improve the biodiversity that’s lost, resulting in a net increase in the quality and quantity of habitats.

What are the key principles of Biodiversity Net Gain?

• Before and after development, biodiversity is quantified using a standardised metric. In England, this is the Defra Biodiversity Metric (currently version 4.0).
• Developers should first avoid harming important habitats, then minimise unavoidable impacts and finally compensate by restoring or creating habitats elsewhere.
• Legally most developments in England must deliver at least a 10% net gain in biodiversity compared to the pre-development baseline.
• Habitat improvements must be secured for at least 30 years, through planning conditions, legal agreements or conservation covenants.

Suppose a housing development removes grassland worth 100 biodiversity units. To meet a 10% net gain, the developer must create or enhance habitats equal to 110 units. This can be either on site, nearby, or (if necessary) by purchasing off site biodiversity credits.

Is Biodiversity Net Gain mandatory?

Yes, BNG became mandatory in England under the Environment Act 2021. It applies to most new planning applications, except for certain small or exempt developments. The scheme is regulated by Natural England and local planning authorities.

Why is BNG important?

BNG helps reverse decades of habitat loss with new woodlands, wetlands, meadows and green corridors to support wildlife.

By creating more and better quality habitats, BNG encourages the return of pollinators, birds and other species. Healthier ecosystems help regulate water, air, and soil - all essential for human wellbeing. Parks, ponds, and nature areas also make neighbourhoods more attractive and enjoyable for residents.

BNG creates a balance between building new homes and protecting nature. It pushes developers to plan more thoughtfully and design with the environment in mind.

What actions are developers taking to meet Biodiversity Net Gain targets?

Meeting Biodiversity Net Gain (BNG) targets isn’t just about planting a few trees. It’s a structured process that uses measurable actions to enhance habitats, support wildlife and create long term ecological value.

Examples of BNG measures include:

• Restoring wildflower meadows or grasslands
• Creating new ponds, wetlands or reedbeds
• Planting native woodlands or hedgerows using native species
• Improving the quality and condition of existing habitats
• Designing layouts to protect mature trees, hedgerows and waterways
• Setting up buffer zones around valuable habitats
• Translocating species or habitats when unavoidable
• Tree planting using native species
• Green roofs and walls to support pollinators and birds
• Sustainable drainage systems with wildlife friendly ponds or rain gardens
• Street and garden planting designed to support biodiversity year round
• Hedgehog highways
• Bird and bat boxes on buildings
• Insect hotels and log piles
• Natural flood management using vegetation and contours

How can I find out what BNG measures have been implemented on a development?

There are several ways to find out about the Biodiversity Net Gain measures in individual developments, including checking the planning application documents, reading the development description on development pages on newhomesforsale.co.uk, or if the information is hard to find you can contact the developer directly.

We have made it easier to find sustainability measures of developments with our green features page, with icons displayed within the description if the information is available.

Natural England is setting up a national biodiversity gain register to track where and how BNG units are being delivered. Once fully operational, this will make it easier to see the full specification of BNG measures.

“When land is developed for housing or infrastructure, the developer must replace and improve the biodiversity that’s lost, resulting in a net increase in the quality and quantity of habitats.”

The future of development

Biodiversity Net Gain represents a real shift in how we think about development, from simply limiting damage to actively improving the natural world alongside new homes and infrastructure. While it’s still early days for implementation, BNG has the potential to make every planning decision part of a wider story of nature recovery. It is a real opportunity to build places where people and wildlife can thrive together for generations to come.

For further information about Biodiversity Net Gain, take a look at the Government’s dedicated BNG website.